Shane already linked the SVS if you missed it.
Example the compact sealed model SB1000 is on sale and probably something you could fit nicely without wife giving you hard time. There is also the newer SB1000 Pro model which is phone app controlled and has a complete new design for a little bit more. Big step up from the slim Kef or any of these usual package woofers. SVS is well known from superb customer service/support and amp warranty is 5 years!
SVS | AV.com
www.av.com
AVForums reviewed the latest Pro model, read up:
Review of the SVS SB-1000 Pro Subwoofer
www.avforums.com
And the "old" SB1000 with the SVS Prime speakers:
SVS launch their new Prime 5.1 sub/sat speaker system.
www.avforums.com
If you go with the Kef T-serie make sure you choose the taller T301 and T301c for LCR, T101 should be fine for surround duties. Personally i would look in to MA Radius 225 or Apex range which both should be step up from the ultra slim Kefs. Dali Oberon On-Wall would be great option, but Dali made big mistake not offering to sell these as single / specific horizontal On-Wall centre. If possible choose Denon X2700H as it doesn`t cost much more than X1700H. Contact the dealer so you get some kind of package deal as you spending 2,5-3k£!